
/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_stream.h>


#define ngx_stream_upstream_tries(p) \
    ((p)->number + ((p)->next ? (p)->next->number : 0))


static ngx_stream_upstream_rr_peer_t *
ngx_stream_upstream_get_peer(ngx_stream_upstream_rr_peer_data_t *rrp);
static void
ngx_stream_upstream_notify_round_robin_peer(ngx_peer_connection_t *pc,
                                            void *data, ngx_uint_t state);

#if (NGX_STREAM_SSL)

static ngx_int_t
ngx_stream_upstream_set_round_robin_peer_session(ngx_peer_connection_t *pc,
                                                 void                  *data);
static void
ngx_stream_upstream_save_round_robin_peer_session(ngx_peer_connection_t *pc,
                                                  void                  *data);
static ngx_int_t
ngx_stream_upstream_empty_set_session(ngx_peer_connection_t *pc, void *data);
static void ngx_stream_upstream_empty_save_session(ngx_peer_connection_t *pc,
                                                   void                  *data);

#endif


ngx_int_t
ngx_stream_upstream_init_round_robin(ngx_conf_t                     *cf,
                                     ngx_stream_upstream_srv_conf_t *us)
{
    ngx_url_t                       u;
    ngx_uint_t                      i, j, n, w;
    ngx_stream_upstream_server_t   *server;
    ngx_stream_upstream_rr_peer_t  *peer, **peerp;
    ngx_stream_upstream_rr_peers_t *peers, *backup;

    us->peer.init = ngx_stream_upstream_init_round_robin_peer;

    if (us->servers)
    {
        server = us->servers->elts;

        n = 0;
        w = 0;

        for (i = 0; i < us->servers->nelts; i++)
        {
            if (server[i].backup)
            {
                continue;
            }

            n += server[i].naddrs;
            w += server[i].naddrs * server[i].weight;
        }

        if (n == 0)
        {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no servers in upstream \"%V\" in %s:%ui", &us->host,
                          us->file_name, us->line);
            return NGX_ERROR;
        }

        peers = ngx_pcalloc(cf->pool, sizeof(ngx_stream_upstream_rr_peers_t));
        if (peers == NULL)
        {
            return NGX_ERROR;
        }

        peer = ngx_pcalloc(cf->pool, sizeof(ngx_stream_upstream_rr_peer_t) * n);
        if (peer == NULL)
        {
            return NGX_ERROR;
        }

        peers->single       = (n == 1);
        peers->number       = n;
        peers->weighted     = (w != n);
        peers->total_weight = w;
        peers->name         = &us->host;

        n     = 0;
        peerp = &peers->peer;

        for (i = 0; i < us->servers->nelts; i++)
        {
            if (server[i].backup)
            {
                continue;
            }

            for (j = 0; j < server[i].naddrs; j++)
            {
                peer[n].sockaddr         = server[i].addrs[j].sockaddr;
                peer[n].socklen          = server[i].addrs[j].socklen;
                peer[n].name             = server[i].addrs[j].name;
                peer[n].weight           = server[i].weight;
                peer[n].effective_weight = server[i].weight;
                peer[n].current_weight   = 0;
                peer[n].max_conns        = server[i].max_conns;
                peer[n].max_fails        = server[i].max_fails;
                peer[n].fail_timeout     = server[i].fail_timeout;
                peer[n].down             = server[i].down;
                peer[n].server           = server[i].name;

                *peerp = &peer[n];
                peerp  = &peer[n].next;
                n++;
            }
        }

        us->peer.data = peers;

        /* backup servers */

        n = 0;
        w = 0;

        for (i = 0; i < us->servers->nelts; i++)
        {
            if (!server[i].backup)
            {
                continue;
            }

            n += server[i].naddrs;
            w += server[i].naddrs * server[i].weight;
        }

        if (n == 0)
        {
            return NGX_OK;
        }

        backup = ngx_pcalloc(cf->pool, sizeof(ngx_stream_upstream_rr_peers_t));
        if (backup == NULL)
        {
            return NGX_ERROR;
        }

        peer = ngx_pcalloc(cf->pool, sizeof(ngx_stream_upstream_rr_peer_t) * n);
        if (peer == NULL)
        {
            return NGX_ERROR;
        }

        peers->single        = 0;
        backup->single       = 0;
        backup->number       = n;
        backup->weighted     = (w != n);
        backup->total_weight = w;
        backup->name         = &us->host;

        n     = 0;
        peerp = &backup->peer;

        for (i = 0; i < us->servers->nelts; i++)
        {
            if (!server[i].backup)
            {
                continue;
            }

            for (j = 0; j < server[i].naddrs; j++)
            {
                peer[n].sockaddr         = server[i].addrs[j].sockaddr;
                peer[n].socklen          = server[i].addrs[j].socklen;
                peer[n].name             = server[i].addrs[j].name;
                peer[n].weight           = server[i].weight;
                peer[n].effective_weight = server[i].weight;
                peer[n].current_weight   = 0;
                peer[n].max_conns        = server[i].max_conns;
                peer[n].max_fails        = server[i].max_fails;
                peer[n].fail_timeout     = server[i].fail_timeout;
                peer[n].down             = server[i].down;
                peer[n].server           = server[i].name;

                *peerp = &peer[n];
                peerp  = &peer[n].next;
                n++;
            }
        }

        peers->next = backup;

        return NGX_OK;
    }


    /* an upstream implicitly defined by proxy_pass, etc. */

    if (us->port == 0)
    {
        ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                      "no port in upstream \"%V\" in %s:%ui", &us->host,
                      us->file_name, us->line);
        return NGX_ERROR;
    }

    ngx_memzero(&u, sizeof(ngx_url_t));

    u.host = us->host;
    u.port = us->port;

    if (ngx_inet_resolve_host(cf->pool, &u) != NGX_OK)
    {
        if (u.err)
        {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "%s in upstream \"%V\" in %s:%ui", u.err, &us->host,
                          us->file_name, us->line);
        }

        return NGX_ERROR;
    }

    n = u.naddrs;

    peers = ngx_pcalloc(cf->pool, sizeof(ngx_stream_upstream_rr_peers_t));
    if (peers == NULL)
    {
        return NGX_ERROR;
    }

    peer = ngx_pcalloc(cf->pool, sizeof(ngx_stream_upstream_rr_peer_t) * n);
    if (peer == NULL)
    {
        return NGX_ERROR;
    }

    peers->single       = (n == 1);
    peers->number       = n;
    peers->weighted     = 0;
    peers->total_weight = n;
    peers->name         = &us->host;

    peerp = &peers->peer;

    for (i = 0; i < u.naddrs; i++)
    {
        peer[i].sockaddr         = u.addrs[i].sockaddr;
        peer[i].socklen          = u.addrs[i].socklen;
        peer[i].name             = u.addrs[i].name;
        peer[i].weight           = 1;
        peer[i].effective_weight = 1;
        peer[i].current_weight   = 0;
        peer[i].max_conns        = 0;
        peer[i].max_fails        = 1;
        peer[i].fail_timeout     = 10;
        *peerp                   = &peer[i];
        peerp                    = &peer[i].next;
    }

    us->peer.data = peers;

    /* implicitly defined upstream has no backup servers */

    return NGX_OK;
}


ngx_int_t
ngx_stream_upstream_init_round_robin_peer(ngx_stream_session_t           *s,
                                          ngx_stream_upstream_srv_conf_t *us)
{
    ngx_uint_t                          n;
    ngx_stream_upstream_rr_peer_data_t *rrp;

    rrp = s->upstream->peer.data;

    if (rrp == NULL)
    {
        rrp = ngx_palloc(s->connection->pool,
                         sizeof(ngx_stream_upstream_rr_peer_data_t));
        if (rrp == NULL)
        {
            return NGX_ERROR;
        }

        s->upstream->peer.data = rrp;
    }

    rrp->peers   = us->peer.data;
    rrp->current = NULL;
    rrp->config  = 0;

    n = rrp->peers->number;

    if (rrp->peers->next && rrp->peers->next->number > n)
    {
        n = rrp->peers->next->number;
    }

    if (n <= 8 * sizeof(uintptr_t))
    {
        rrp->tried = &rrp->data;
        rrp->data  = 0;
    }
    else
    {
        n = (n + (8 * sizeof(uintptr_t) - 1)) / (8 * sizeof(uintptr_t));

        rrp->tried = ngx_pcalloc(s->connection->pool, n * sizeof(uintptr_t));
        if (rrp->tried == NULL)
        {
            return NGX_ERROR;
        }
    }

    s->upstream->peer.get    = ngx_stream_upstream_get_round_robin_peer;
    s->upstream->peer.free   = ngx_stream_upstream_free_round_robin_peer;
    s->upstream->peer.notify = ngx_stream_upstream_notify_round_robin_peer;
    s->upstream->peer.tries  = ngx_stream_upstream_tries(rrp->peers);
#if (NGX_STREAM_SSL)
    s->upstream->peer.set_session =
        ngx_stream_upstream_set_round_robin_peer_session;
    s->upstream->peer.save_session =
        ngx_stream_upstream_save_round_robin_peer_session;
#endif

    return NGX_OK;
}


ngx_int_t
ngx_stream_upstream_create_round_robin_peer(ngx_stream_session_t           *s,
                                            ngx_stream_upstream_resolved_t *ur)
{
    u_char                             *p;
    size_t                              len;
    socklen_t                           socklen;
    ngx_uint_t                          i, n;
    struct sockaddr                    *sockaddr;
    ngx_stream_upstream_rr_peer_t      *peer, **peerp;
    ngx_stream_upstream_rr_peers_t     *peers;
    ngx_stream_upstream_rr_peer_data_t *rrp;

    rrp = s->upstream->peer.data;

    if (rrp == NULL)
    {
        rrp = ngx_palloc(s->connection->pool,
                         sizeof(ngx_stream_upstream_rr_peer_data_t));
        if (rrp == NULL)
        {
            return NGX_ERROR;
        }

        s->upstream->peer.data = rrp;
    }

    peers = ngx_pcalloc(s->connection->pool,
                        sizeof(ngx_stream_upstream_rr_peers_t));
    if (peers == NULL)
    {
        return NGX_ERROR;
    }

    peer = ngx_pcalloc(s->connection->pool,
                       sizeof(ngx_stream_upstream_rr_peer_t) * ur->naddrs);
    if (peer == NULL)
    {
        return NGX_ERROR;
    }

    peers->single = (ur->naddrs == 1);
    peers->number = ur->naddrs;
    peers->name   = &ur->host;

    if (ur->sockaddr)
    {
        peer[0].sockaddr         = ur->sockaddr;
        peer[0].socklen          = ur->socklen;
        peer[0].name             = ur->name;
        peer[0].weight           = 1;
        peer[0].effective_weight = 1;
        peer[0].current_weight   = 0;
        peer[0].max_conns        = 0;
        peer[0].max_fails        = 1;
        peer[0].fail_timeout     = 10;
        peers->peer              = peer;
    }
    else
    {
        peerp = &peers->peer;

        for (i = 0; i < ur->naddrs; i++)
        {
            socklen = ur->addrs[i].socklen;

            sockaddr = ngx_palloc(s->connection->pool, socklen);
            if (sockaddr == NULL)
            {
                return NGX_ERROR;
            }

            ngx_memcpy(sockaddr, ur->addrs[i].sockaddr, socklen);
            ngx_inet_set_port(sockaddr, ur->port);

            p = ngx_pnalloc(s->connection->pool, NGX_SOCKADDR_STRLEN);
            if (p == NULL)
            {
                return NGX_ERROR;
            }

            len = ngx_sock_ntop(sockaddr, socklen, p, NGX_SOCKADDR_STRLEN, 1);

            peer[i].sockaddr         = sockaddr;
            peer[i].socklen          = socklen;
            peer[i].name.len         = len;
            peer[i].name.data        = p;
            peer[i].weight           = 1;
            peer[i].effective_weight = 1;
            peer[i].current_weight   = 0;
            peer[i].max_conns        = 0;
            peer[i].max_fails        = 1;
            peer[i].fail_timeout     = 10;
            *peerp                   = &peer[i];
            peerp                    = &peer[i].next;
        }
    }

    rrp->peers   = peers;
    rrp->current = NULL;
    rrp->config  = 0;

    if (rrp->peers->number <= 8 * sizeof(uintptr_t))
    {
        rrp->tried = &rrp->data;
        rrp->data  = 0;
    }
    else
    {
        n = (rrp->peers->number + (8 * sizeof(uintptr_t) - 1))
            / (8 * sizeof(uintptr_t));

        rrp->tried = ngx_pcalloc(s->connection->pool, n * sizeof(uintptr_t));
        if (rrp->tried == NULL)
        {
            return NGX_ERROR;
        }
    }

    s->upstream->peer.get   = ngx_stream_upstream_get_round_robin_peer;
    s->upstream->peer.free  = ngx_stream_upstream_free_round_robin_peer;
    s->upstream->peer.tries = ngx_stream_upstream_tries(rrp->peers);
#if (NGX_STREAM_SSL)
    s->upstream->peer.set_session  = ngx_stream_upstream_empty_set_session;
    s->upstream->peer.save_session = ngx_stream_upstream_empty_save_session;
#endif

    return NGX_OK;
}


ngx_int_t
ngx_stream_upstream_get_round_robin_peer(ngx_peer_connection_t *pc, void *data)
{
    ngx_stream_upstream_rr_peer_data_t *rrp = data;

    ngx_int_t                       rc;
    ngx_uint_t                      i, n;
    ngx_stream_upstream_rr_peer_t  *peer;
    ngx_stream_upstream_rr_peers_t *peers;

    ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0, "get rr peer, try: %ui",
                   pc->tries);

    pc->connection = NULL;

    peers = rrp->peers;
    ngx_stream_upstream_rr_peers_wlock(peers);

    if (peers->single)
    {
        peer = peers->peer;

        if (peer->down)
        {
            goto failed;
        }

        if (peer->max_conns && peer->conns >= peer->max_conns)
        {
            goto failed;
        }

        rrp->current = peer;
    }
    else
    {
        /* there are several peers */

        peer = ngx_stream_upstream_get_peer(rrp);

        if (peer == NULL)
        {
            goto failed;
        }

        ngx_log_debug2(NGX_LOG_DEBUG_STREAM, pc->log, 0,
                       "get rr peer, current: %p %i", peer,
                       peer->current_weight);
    }

    pc->sockaddr = peer->sockaddr;
    pc->socklen  = peer->socklen;
    pc->name     = &peer->name;

    peer->conns++;

    ngx_stream_upstream_rr_peers_unlock(peers);

    return NGX_OK;

failed:

    if (peers->next)
    {
        ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0, "backup servers");

        rrp->peers = peers->next;

        n = (rrp->peers->number + (8 * sizeof(uintptr_t) - 1))
            / (8 * sizeof(uintptr_t));

        for (i = 0; i < n; i++)
        {
            rrp->tried[i] = 0;
        }

        ngx_stream_upstream_rr_peers_unlock(peers);

        rc = ngx_stream_upstream_get_round_robin_peer(pc, rrp);

        if (rc != NGX_BUSY)
        {
            return rc;
        }

        ngx_stream_upstream_rr_peers_wlock(peers);
    }

    ngx_stream_upstream_rr_peers_unlock(peers);

    pc->name = peers->name;

    return NGX_BUSY;
}


static ngx_stream_upstream_rr_peer_t *
ngx_stream_upstream_get_peer(ngx_stream_upstream_rr_peer_data_t *rrp)
{
    time_t                         now;
    uintptr_t                      m;
    ngx_int_t                      total;
    ngx_uint_t                     i, n, p;
    ngx_stream_upstream_rr_peer_t *peer, *best;

    now = ngx_time();

    best  = NULL;
    total = 0;

#if (NGX_SUPPRESS_WARN)
    p = 0;
#endif

    for (peer = rrp->peers->peer, i = 0; peer; peer = peer->next, i++)
    {
        n = i / (8 * sizeof(uintptr_t));
        m = (uintptr_t)1 << i % (8 * sizeof(uintptr_t));

        if (rrp->tried[n] & m)
        {
            continue;
        }

        if (peer->down)
        {
            continue;
        }

        if (peer->max_fails && peer->fails >= peer->max_fails
            && now - peer->checked <= peer->fail_timeout)
        {
            continue;
        }

        if (peer->max_conns && peer->conns >= peer->max_conns)
        {
            continue;
        }

        peer->current_weight += peer->effective_weight;
        total += peer->effective_weight;

        if (peer->effective_weight < peer->weight)
        {
            peer->effective_weight++;
        }

        if (best == NULL || peer->current_weight > best->current_weight)
        {
            best = peer;
            p    = i;
        }
    }

    if (best == NULL)
    {
        return NULL;
    }

    rrp->current = best;

    n = p / (8 * sizeof(uintptr_t));
    m = (uintptr_t)1 << p % (8 * sizeof(uintptr_t));

    rrp->tried[n] |= m;

    best->current_weight -= total;

    if (now - best->checked > best->fail_timeout)
    {
        best->checked = now;
    }

    return best;
}


void
ngx_stream_upstream_free_round_robin_peer(ngx_peer_connection_t *pc, void *data,
                                          ngx_uint_t state)
{
    ngx_stream_upstream_rr_peer_data_t *rrp = data;

    time_t                         now;
    ngx_stream_upstream_rr_peer_t *peer;

    ngx_log_debug2(NGX_LOG_DEBUG_STREAM, pc->log, 0, "free rr peer %ui %ui",
                   pc->tries, state);

    peer = rrp->current;

    ngx_stream_upstream_rr_peers_rlock(rrp->peers);
    ngx_stream_upstream_rr_peer_lock(rrp->peers, peer);

    if (rrp->peers->single)
    {
        peer->conns--;

        ngx_stream_upstream_rr_peer_unlock(rrp->peers, peer);
        ngx_stream_upstream_rr_peers_unlock(rrp->peers);

        pc->tries = 0;
        return;
    }

    if (state & NGX_PEER_FAILED)
    {
        now = ngx_time();

        peer->fails++;
        peer->accessed = now;
        peer->checked  = now;

        if (peer->max_fails)
        {
            peer->effective_weight -= peer->weight / peer->max_fails;

            if (peer->fails >= peer->max_fails)
            {
                ngx_log_error(NGX_LOG_WARN, pc->log, 0,
                              "upstream server temporarily disabled");
            }
        }

        ngx_log_debug2(NGX_LOG_DEBUG_STREAM, pc->log, 0,
                       "free rr peer failed: %p %i", peer,
                       peer->effective_weight);

        if (peer->effective_weight < 0)
        {
            peer->effective_weight = 0;
        }
    }
    else
    {
        /* mark peer live if check passed */

        if (peer->accessed < peer->checked)
        {
            peer->fails = 0;
        }
    }

    peer->conns--;

    ngx_stream_upstream_rr_peer_unlock(rrp->peers, peer);
    ngx_stream_upstream_rr_peers_unlock(rrp->peers);

    if (pc->tries)
    {
        pc->tries--;
    }
}


static void
ngx_stream_upstream_notify_round_robin_peer(ngx_peer_connection_t *pc,
                                            void *data, ngx_uint_t type)
{
    ngx_stream_upstream_rr_peer_data_t *rrp = data;

    ngx_stream_upstream_rr_peer_t *peer;

    peer = rrp->current;

    if (type == NGX_STREAM_UPSTREAM_NOTIFY_CONNECT
        && pc->connection->type == SOCK_STREAM)
    {
        ngx_stream_upstream_rr_peers_rlock(rrp->peers);
        ngx_stream_upstream_rr_peer_lock(rrp->peers, peer);

        if (peer->accessed < peer->checked)
        {
            peer->fails = 0;
        }

        ngx_stream_upstream_rr_peer_unlock(rrp->peers, peer);
        ngx_stream_upstream_rr_peers_unlock(rrp->peers);
    }
}


#if (NGX_STREAM_SSL)

static ngx_int_t
ngx_stream_upstream_set_round_robin_peer_session(ngx_peer_connection_t *pc,
                                                 void                  *data)
{
    ngx_stream_upstream_rr_peer_data_t *rrp = data;

    ngx_int_t                      rc;
    ngx_ssl_session_t             *ssl_session;
    ngx_stream_upstream_rr_peer_t *peer;
#if (NGX_STREAM_UPSTREAM_ZONE)
    int                             len;
    const u_char                   *p;
    ngx_stream_upstream_rr_peers_t *peers;
    u_char                          buf[NGX_SSL_MAX_SESSION_SIZE];
#endif

    peer = rrp->current;

#if (NGX_STREAM_UPSTREAM_ZONE)
    peers = rrp->peers;

    if (peers->shpool)
    {
        ngx_stream_upstream_rr_peers_rlock(peers);
        ngx_stream_upstream_rr_peer_lock(peers, peer);

        if (peer->ssl_session == NULL)
        {
            ngx_stream_upstream_rr_peer_unlock(peers, peer);
            ngx_stream_upstream_rr_peers_unlock(peers);
            return NGX_OK;
        }

        len = peer->ssl_session_len;

        ngx_memcpy(buf, peer->ssl_session, len);

        ngx_stream_upstream_rr_peer_unlock(peers, peer);
        ngx_stream_upstream_rr_peers_unlock(peers);

        p           = buf;
        ssl_session = d2i_SSL_SESSION(NULL, &p, len);

        rc = ngx_ssl_set_session(pc->connection, ssl_session);

        ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0, "set session: %p",
                       ssl_session);

        ngx_ssl_free_session(ssl_session);

        return rc;
    }
#endif

    ssl_session = peer->ssl_session;

    rc = ngx_ssl_set_session(pc->connection, ssl_session);

    ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0, "set session: %p",
                   ssl_session);

    return rc;
}


static void
ngx_stream_upstream_save_round_robin_peer_session(ngx_peer_connection_t *pc,
                                                  void                  *data)
{
    ngx_stream_upstream_rr_peer_data_t *rrp = data;

    ngx_ssl_session_t             *old_ssl_session, *ssl_session;
    ngx_stream_upstream_rr_peer_t *peer;
#if (NGX_STREAM_UPSTREAM_ZONE)
    int                             len;
    u_char                         *p;
    ngx_stream_upstream_rr_peers_t *peers;
    u_char                          buf[NGX_SSL_MAX_SESSION_SIZE];
#endif

#if (NGX_STREAM_UPSTREAM_ZONE)
    peers = rrp->peers;

    if (peers->shpool)
    {
        ssl_session = ngx_ssl_get0_session(pc->connection);

        if (ssl_session == NULL)
        {
            return;
        }

        ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0, "save session: %p",
                       ssl_session);

        len = i2d_SSL_SESSION(ssl_session, NULL);

        /* do not cache too big session */

        if (len > NGX_SSL_MAX_SESSION_SIZE)
        {
            return;
        }

        p = buf;
        (void)i2d_SSL_SESSION(ssl_session, &p);

        peer = rrp->current;

        ngx_stream_upstream_rr_peers_rlock(peers);
        ngx_stream_upstream_rr_peer_lock(peers, peer);

        if (len > peer->ssl_session_len)
        {
            ngx_shmtx_lock(&peers->shpool->mutex);

            if (peer->ssl_session)
            {
                ngx_slab_free_locked(peers->shpool, peer->ssl_session);
            }

            peer->ssl_session = ngx_slab_alloc_locked(peers->shpool, len);

            ngx_shmtx_unlock(&peers->shpool->mutex);

            if (peer->ssl_session == NULL)
            {
                peer->ssl_session_len = 0;

                ngx_stream_upstream_rr_peer_unlock(peers, peer);
                ngx_stream_upstream_rr_peers_unlock(peers);
                return;
            }

            peer->ssl_session_len = len;
        }

        ngx_memcpy(peer->ssl_session, buf, len);

        ngx_stream_upstream_rr_peer_unlock(peers, peer);
        ngx_stream_upstream_rr_peers_unlock(peers);

        return;
    }
#endif

    ssl_session = ngx_ssl_get_session(pc->connection);

    if (ssl_session == NULL)
    {
        return;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0, "save session: %p",
                   ssl_session);

    peer = rrp->current;

    old_ssl_session   = peer->ssl_session;
    peer->ssl_session = ssl_session;

    if (old_ssl_session)
    {
        ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0, "old session: %p",
                       old_ssl_session);

        /* TODO: may block */

        ngx_ssl_free_session(old_ssl_session);
    }
}


static ngx_int_t
ngx_stream_upstream_empty_set_session(ngx_peer_connection_t *pc, void *data)
{
    return NGX_OK;
}


static void
ngx_stream_upstream_empty_save_session(ngx_peer_connection_t *pc, void *data)
{
    return;
}

#endif
